Rudolph c



nif sr Lrits Para UNlVEBiSAL PLOTTENG INSTRUMENT Specicatn of Letters Patent.

Application' mea-Jene so, 1ere; serial n. 307,797;

(FILED entrenar-nerernment, ieeafaasrar; n, est.)

D. C., have invented an Improvement; in Universal; Plotting` lnstrmnents, `ot which the following fis a speciication The invention described" hereinV mayV be used bythefGovernment, or anyiofits oiil eers or employees 1n prosecution ot Worhfior the Government, .or by any foth'er" person lin the United States, Without paymentotfany" royalty f thereon` lllhis 1 invention relates to a universaliplots ting instrument i for use "in military sketch# i11g:inthef lield; Where the slretcherhas to "del pend ontl a fevv instruments, Whiclrlmust be easily carriedu` and capable of! withstanding jl accuracy `With the instrttments ai'failableg andi one obj ect?` of? this invention is 1 to provide Va` plotti1ig ins-t1umentwhich meets the requiref ments asfto us age inthe lfield which 1also= enables the 1 sketcherf to -lplot distances on the sketchwvith a negligiblellerror i Another object of this* invention Lis tolypro``v vide an instrument 1 vvhiclr Will enable" ai map i reader to scale distancekfiom the map with; greater accuracy" and *facilityi lthas been found that fer a scale faslarg'e f as 43 to themile` orf` even 6" to the-mile, the closestreading that can beA obtained lis `about 25 ipaeeis, with the instruments novv in 1 use With 1this devicetit isf possible f to "read map distances tot `Within ltvvo or three* pacesgfz this l result being-obtainedby atmagnifying' ell'ecty which forme feature"-` oil` this instrument. The advantage to be gained "infths connec` tion 4Will bereadilyunderstoodl y Another* advantage inthe use* of this plotting-finstriunentl is that itslapplicatiorr isuni#` versal for` allmap scales new? inf nse. It can be `usedvto plot 1 `feet, yards ord` meters, ori cani be used to read feet,:yartlslformeters from a: map With but one settingv 'of thewclampmg device.

In the preferred forrnthe` device is z` compact 1 and conveniently carried, `having f been 1 For" a clearer understanding,` ofthe invention reference is made to the accompanying` drawings, inlvvhichp liligan'e f1 is a plan view otone embodiment oflthe invention;

Fligx Qfis a side elevation et the device with the main legs closed Figtlisa cross-sectionalview (line 35e-3" of lig'l) through oneo'l thefmain legs, shetving `the small movable arm in its closed position; i

'lil-igzfl-` isa cross-sectional view substantiallyonkthel line 1% through the" pivot oi" the smallfmovable arm', but with the arm in its closed lposition.

ln the device as shown there are provided tvvo main legs, `designated on the drawings as 1 and 2, held together by apivot member 3,

provided with a clamping-nut el; rllhe pivot member isvmountedito be movablein slots 5 and 6, cut longitudinally inthe legs land 2, respectively; rlhe pivot member 3 and clampingnnutd are so" constructed that When the mit` elwhas `been tightened the member 3 is prevented from sliding relative to the legs 1 and 2-that is, the point on which said legs pivotlis `hitech-but the legs11 and 2 are not prevented from pivotal motion about member 3. The legs 1* and 2 areprovided at one end with sharp points, 7 "and 8. rttached` to the pivot member 3 and movable With themember 3 along-the slot 5 in the leg` is amember 9, bearing a* zero marlror index.

Attire end of the legi` 2, opposite to the point 8, is a movable arm. 10, pivotally mounted by means oia pivot 11 on `the cen ter line of the legQ; i. This `armis movable to fit in a recess 12, cut in the leg` 2. Recess 12 is providedso thatthe arm 10 may be placed in a position of safety when the instrument is folded and notlin use.` The arm 10 is provided, along the inside edge, vvith graduw tions comprising" a scale 13, divided y into suitahilelnnits; The use otp'these` graduations Will be more inlly explained hereinafter. The legA 11is providedat the end thereof, opposite the point? Witlrapoint 141-, which is designed to indicate readings along` the scale 13;

The leg,` lis provided with two series ot" ratentea new ie, raie.,

values of map sca-les and series 16 the length of pace in inches.

The calculation of the size of the units of the various scales may be explained as follows. For the sake of convenience, the length of the leg 1, which may be called the index leg, may be made 10 inches from the tip of point 7 to the tip of point 14;. The length of the leg 2 is also made 10 inches from the tip of point 8 to the center of pivot 11. The movable arm 10 is arbitrarily made 3 inches in length and divided into arbitrary units as shown on the sketch.

The graduations on index arm 1 are 0btained as follows:

lVith 3 on the graduated arm 10 having been given a valve of 500 paces, then 100 paces will be equal to if; of 3 or 0.6 inch. Now, in order that the lower points of the instrument may be separated a distance which shall correspond, on a map of 3 equals 1 mile scale, for instance, to 100 paces oi' a given length, it is necessary to set the pivot at such a point that in the similar triangles formed between the arms of the instrument, the bases shall be, respectively, 0.6 inch on the upper triangle and on the lower a length which represents 100 paces on the map.

Assuming again a map scale of 3 inches equals l mile, then,

1 mile groundz map.

l l2 5280 in. ground:63,360 groundz map.

1 in. ground:1/21,120 in. map.

The fraction 1/21,120 is the representative fraction of the map for the scale designated.

Now let azthe length of pace in inches, and

Let bzthe representative fraction of the map.

From the assumption above 1 in. ground equals b in. on the map.

Then 1 pace groundza. b. in. on the map.

And 100 paces ground:100 a. b. in. map.

Now let Xzthe distance in inches from the point 7 on the index leg to the pivot.

Then 10-Xzthe distance in inches from the pivot to the point 14.

Then by similar triangles x: (1o-x) 100 a. bzo Y Solving 1000 a. b. .6-1- 100 a, b.

This formula furnishes the basis for calculation of the distance from the point 7 of the location of the pivot and this distance, it will be noted, may be calculated for various pace lengths and map scales. It will be noted further that cach distance is a matter of separate computation and it is not possi-ble to obtain these values by proportion.

There have been placed on the leg l,

graduations for the following 6 map scales:

3:1 mile. 6:1 mile.

12:1 mile.

Also scales with representative fractions of 1/20,000, 1/10,000, and 1/5,000.

.For plotting feet on the iirst 3 map scales, the 24 in. pace is used, the readings on the` movable arm being doubled. The 86 pace gives the readings in yards. For use in connection with the last three map scales, a point M has been marked indicating a pace 1 meter long.

Inasmuch as the pivot 3 cannot be satisfactorily used as a zero mark, a member 9 has been provided, attached to member 3 and movable slidably with it. Member 9 has located upon its surface a zero mark at a distance of inch from the pivot, and all measurements therefore must be made from a point an inch inside the point of the leg 1.

The directions for using the instrument are very simple and printed on the index leg 1. The sketcher determines by trial the average length of his pace and then sets the zero at the number indicating the length of his pace for the scale of the map he desires to plot. The pivot is then clamped and remains fixed as long as the same scale is to be used. To plot any number of paces up to 500 with the clamp fixed at the proper length of pace and scale of map, the index leg l is moved until a reading of the correct number of paces on the pace scale of the movable arm is obtained. The points of the instrument are then placed on the map and the distance between the points on the paper will be the correct map distance. To read the distance in paces between any two points on the map the legs are clamped, as described above, according to the scale of the map and the length of pace and the readings made on the scale of the movable arm.

It will be understood that the invention is not limited in this description to the measurements as given2 and that the device is capable of use in various modifications, of which the preferred form is shown.

What I claim as new and desire to secure by Letters Patent is:

l. A. plotting instrument having two divider legs, one of said legs provided with a recessed portion, a pivot connecting said legs and adjustable longitudinally thereon, and an arm pivoted on said leg and movable to enter the recessed portion of said leg.

2. A plotting instrument having two divider legs one of which is provided with graduations, a pivot connecting said legs and adjustable longitudinally thereon, a member mounted on said pivot and bearing an nations.

3. A plotting instrument having two divider legs, one of said legs bearing a plurality of scales, a pivot connecting said legs and adjustable longitudinally theren,' a member mounted on said pivot, and an in dex on said member, adapted to ooperato with any desired scale on said leg.

l. A plotting instrument having two divider legs, one of said legs bearing a plu rality of scales, a pivot connecting said legs and adjustable longitudinally thereon, a member mounted on said pivot, an index on said member adapted to cooperate With a predetermined scale on said leg, and" an arm pivoted on said second leg, said leg being provided with means to protect said arm, when in the folded position.

5. A plotting instrument, having two divider legs, one of said legs bearing a plurality o'f scales, said leg terminating in an index pointer, a pivot connecting said legs and adjustable longitudinally thereon, a

member mounted on said pivot, an index on said member adapted to coperate with a predetermined scale on said leg, a graduated arm pivoted on said second leg, and a scale on said arm, said arm being movable to cooperate with the index pointer on said first gd. A plotting instrument having tWo divider legs, one of said legs bearing a plurality of scales, a pivot connecting said legs and adjustable longitudinally thereon, said pivot being adapted to lock said legs against longitudinal movement in any desired relative position, but permitting free angular movement, a member mounted on said pivot, an index on saidinember adapted to coperate with a predetermined scale on said leg, and a graduated arm pivoted on the other of said legs, said leg being constructed with a recess to protect said arm when in the folded position.

- RUDOLPH C. KULDELL. 

